The present invention relates to a ribbon feed mechanism for printing machines and more particularly relates to a control mechanism for incrementally feeding a print ribbon in a ribbon cassette.
A known ribbon feed mechanism has a motor coupled to a ribbon drive mechanism by a slip clutch for advancing a print ribbon from a supply spool to a take-up spool. A control mechanism including a stepping magnet is connected to the print ribbon for limiting the amount of ribbon feed to predetermined feed increments. This ribbon feed mechanism is disclosed in U.S. Pat. No. 3,481,446 issued on Dec. 2, 1969 and invented by Gisbert Burkhardt et al.
A disadvantage of this ribbon feed mechanism is having a stepping magnet and having a means for selectively energizing the stepping magnet in addition to the motor for advancing the ribbon results in excessive manufacturing costs.
A known linespacing mechanism has a D.C. motor coupled to a drive member which includes a cam profile having a cam surface and an abutment. The linespacing mechanism has a cam follower for following the cam surface to provide a power source for actuating linespacing increments. The cam follower also contacts the abutment for stopping the drive mechanism. This linespacing mechanism is disclosed in U.S. Pat. No. 4,365,904 issued on Dec. 28, 1982 and invented by Hans W. Mueller et al.
A disadvantage of this linespacing mechanism is having the cam follower provide the power source for actuating the linespacing requires additional linkage compared to the present invention which results in excessive manufacturing costs.